man/resolvectl.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   This file is part of systemd.
   9
  10   Copyright 2016 Lennart Poettering
  11 -->
  12
  13 <refentry id="resolvectl" conditional='ENABLE_RESOLVE'
  14           xmlns:xi="http://www.w3.org/2001/XInclude">
  15
  16   <refentryinfo>
  17     <title>resolvectl</title>
  18     <productname>systemd</productname>
  19
  20     <authorgroup>
  21       <author>
  22         <contrib>Developer</contrib>
  23         <firstname>Lennart</firstname>
  24         <surname>Poettering</surname>
  25         <email>lennart@poettering.net</email>
  26       </author>
  27     </authorgroup>
  28   </refentryinfo>
  29
  30   <refmeta>
  31     <refentrytitle>resolvectl</refentrytitle>
  32     <manvolnum>1</manvolnum>
  33   </refmeta>
  34
  35   <refnamediv>
  36     <refname>resolvectl</refname>
  37     <refname>resolvconf</refname>
  38     <refpurpose>Resolve domain names, IPV4 and IPv6 addresses, DNS resource records, and services; introspect and reconfigure the DNS resolver</refpurpose>
  39   </refnamediv>
  40
  41   <refsynopsisdiv>
  42     <cmdsynopsis>
  43       <command>resolvectl</command>
  44       <arg choice="opt" rep="repeat">OPTIONS</arg>
  45       <arg choice="req">COMMAND</arg>
  46       <arg choice="opt" rep="repeat">NAME</arg>
  47     </cmdsynopsis>
  48   </refsynopsisdiv>
  49
  50   <refsect1>
  51     <title>Description</title>
  52
  53     <para><command>resolvectl</command> may be used to resolve domain names, IPv4 and IPv6 addresses, DNS resource
  54     records and services with the
  55     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
  56     resolver service. By default, the specified list of parameters will be resolved as hostnames, retrieving their IPv4
  57     and IPv6 addresses. If the parameters specified are formatted as IPv4 or IPv6 operation the reverse operation is
  58     done, and a hostname is retrieved for the specified addresses.</para>
  59
  60     <para>The program's output contains information about the protocol used for the look-up and on which network
  61     interface the data was discovered. It also contains information on whether the information could be
  62     authenticated. All data for which local DNSSEC validation succeeds is considered authenticated. Moreover all data
  63     originating from local, trusted sources is also reported authenticated, including resolution of the local host
  64     name, the <literal>localhost</literal> host name or all data from <filename>/etc/hosts</filename>.</para>
  65   </refsect1>
  66
  67   <refsect1>
  68     <title>Options</title>
  69     <variablelist>
  70       <varlistentry>
  71         <term><option>-4</option></term>
  72         <term><option>-6</option></term>
  73
  74         <listitem><para>By default, when resolving a hostname, both IPv4 and IPv6
  75         addresses are acquired. By specifying <option>-4</option> only IPv4 addresses are requested, by specifying
  76         <option>-6</option> only IPv6 addresses are requested.</para>
  77         </listitem>
  78       </varlistentry>
  79
  80       <varlistentry>
  81         <term><option>-i</option> <replaceable>INTERFACE</replaceable></term>
  82         <term><option>--interface=</option><replaceable>INTERFACE</replaceable></term>
  83
  84         <listitem><para>Specifies the network interface to execute the query on. This may either be specified as numeric
  85         interface index or as network interface string (e.g. <literal>en0</literal>). Note that this option has no
  86         effect if system-wide DNS configuration (as configured in <filename>/etc/resolv.conf</filename> or
  87         <filename>/etc/systemd/resolve.conf</filename>) in place of per-link configuration is used.</para></listitem>
  88       </varlistentry>
  89
  90       <varlistentry>
  91         <term><option>-p</option> <replaceable>PROTOCOL</replaceable></term>
  92         <term><option>--protocol=</option><replaceable>PROTOCOL</replaceable></term>
  93
  94         <listitem><para>Specifies the network protocol for the query. May be one of <literal>dns</literal>
  95         (i.e. classic unicast DNS), <literal>llmnr</literal> (<ulink
  96         url="https://tools.ietf.org/html/rfc4795">Link-Local Multicast Name Resolution</ulink>),
  97         <literal>llmnr-ipv4</literal>, <literal>llmnr-ipv6</literal> (LLMNR via the indicated underlying IP
  98         protocols), <literal>mdns</literal> (<ulink url="https://www.ietf.org/rfc/rfc6762.txt">Multicast DNS</ulink>),
  99         <literal>mdns-ipv4</literal>, <literal>mdns-ipv6</literal> (MDNS via the indicated underlying IP protocols).
 100         By default the lookup is done via all protocols suitable for the lookup. If used, limits the set of
 101         protocols that may be used. Use this option multiple times to enable resolving via multiple protocols at the
 102         same time. The setting <literal>llmnr</literal> is identical to specifying this switch once with
 103         <literal>llmnr-ipv4</literal> and once via <literal>llmnr-ipv6</literal>. Note that this option does not force
 104         the service to resolve the operation with the specified protocol, as that might require a suitable network
 105         interface and configuration.
 106         The special value <literal>help</literal> may be used to list known values.
 107         </para></listitem>
 108       </varlistentry>
 109
 110       <varlistentry>
 111         <term><option>-t</option> <replaceable>TYPE</replaceable></term>
 112         <term><option>--type=</option><replaceable>TYPE</replaceable></term>
 113         <term><option>-c</option> <replaceable>CLASS</replaceable></term>
 114         <term><option>--class=</option><replaceable>CLASS</replaceable></term>
 115
 116         <listitem><para>Specifies the DNS resource record type (e.g. A, AAAA, MX, …) and class (e.g. IN, ANY, …) to
 117         look up. If these options are used a DNS resource record set matching the specified class and type is
 118         requested. The class defaults to IN if only a type is specified.
 119         The special value <literal>help</literal> may be used to list known values.
 120         </para></listitem>
 121       </varlistentry>
 122
 123       <varlistentry>
 124         <term><option>--service-address=</option><replaceable>BOOL</replaceable></term>
 125
 126         <listitem><para>Takes a boolean parameter. If true (the default), when doing a service lookup with
 127         <option>--service</option> the hostnames contained in the SRV resource records are resolved as well.</para></listitem>
 128       </varlistentry>
 129
 130       <varlistentry>
 131         <term><option>--service-txt=</option><replaceable>BOOL</replaceable></term>
 132
 133         <listitem><para>Takes a boolean parameter. If true (the default), when doing a DNS-SD service lookup with
 134         <option>--service</option> the TXT service metadata record is resolved as well.</para></listitem>
 135       </varlistentry>
 136
 137       <varlistentry>
 138         <term><option>--cname=</option><replaceable>BOOL</replaceable></term>
 139
 140         <listitem><para>Takes a boolean parameter. If true (the default), DNS CNAME or DNAME redirections are
 141         followed. Otherwise, if a CNAME or DNAME record is encountered while resolving, an error is
 142         returned.</para></listitem>
 143       </varlistentry>
 144
 145       <varlistentry>
 146         <term><option>--search=</option><replaceable>BOOL</replaceable></term>
 147
 148         <listitem><para>Takes a boolean parameter. If true (the default), any specified single-label hostnames will be
 149         searched in the domains configured in the search domain list, if it is non-empty. Otherwise, the search domain
 150         logic is disabled.</para></listitem>
 151       </varlistentry>
 152
 153       <varlistentry>
 154         <term><option>--raw</option><optional>=payload|packet</optional></term>
 155
 156         <listitem><para>Dump the answer as binary data. If there is no argument or if the argument is
 157         <literal>payload</literal>, the payload of the packet is exported. If the argument is
 158         <literal>packet</literal>, the whole packet is dumped in wire format, prefixed by
 159         length specified as a little-endian 64-bit number. This format allows multiple packets
 160         to be dumped and unambiguously parsed.</para></listitem>
 161       </varlistentry>
 162
 163       <varlistentry>
 164         <term><option>--legend=</option><replaceable>BOOL</replaceable></term>
 165
 166         <listitem><para>Takes a boolean parameter. If true (the default), column headers and meta information about the
 167         query response are shown. Otherwise, this output is suppressed.</para></listitem>
 168       </varlistentry>
 169
 170       <xi:include href="standard-options.xml" xpointer="help" />
 171       <xi:include href="standard-options.xml" xpointer="version" />
 172       <xi:include href="standard-options.xml" xpointer="no-pager" />
 173     </variablelist>
 174   </refsect1>
 175
 176   <refsect1>
 177     <title>Commands</title>
 178     <variablelist>
 179
 180       <varlistentry>
 181         <term><option>query <replaceable>HOSTNAME|ADDRESS</replaceable>…</option></term>
 182
 183         <listitem><para>Resolve domain names, IPv4 and IPv6 addresses.</para></listitem>
 184       </varlistentry>
 185
 186       <varlistentry>
 187         <term><option>service [[<replaceable>NAME</replaceable>] <replaceable>TYPE</replaceable>] <replaceable>DOMAIN</replaceable></option></term>
 188
 189         <listitem><para>Resolve <ulink url="https://tools.ietf.org/html/rfc6763">DNS-SD</ulink> and
 190         <ulink url="https://tools.ietf.org/html/rfc2782">SRV</ulink> services, depending on the specified list of parameters.
 191         If three parameters are passed the first is assumed to be the DNS-SD service name, the second the SRV service type,
 192         and the third the domain to search in. In this case a full DNS-SD style SRV and TXT lookup is executed. If only two
 193         parameters are specified, the first is assumed to be the SRV service type, and the second the domain to look in. In
 194         this case no TXT RR is requested. Finally, if only one parameter is specified, it is assumed to be a domain name,
 195         that is already prefixed with an SRV type, and an SRV lookup is done (no TXT).</para></listitem>
 196       </varlistentry>
 197
 198       <varlistentry>
 199         <term><option>openpgp <replaceable>EMAIL@DOMAIN</replaceable>…</option></term>
 200
 201         <listitem><para>Query PGP keys stored as <ulink url="https://tools.ietf.org/html/rfc7929">OPENPGPKEY</ulink>
 202         resource records. Specified e-mail addresses are converted to the corresponding DNS domain name, and any
 203         OPENPGPKEY keys are printed.</para></listitem>
 204       </varlistentry>
 205
 206       <varlistentry>
 207         <term><option>tlsa [<replaceable>FAMILY</replaceable>] <replaceable>DOMAIN</replaceable>[:<replaceable>PORT</replaceable>]…</option></term>
 208
 209         <listitem><para>Query TLS public keys stored as <ulink url="https://tools.ietf.org/html/rfc6698">TLSA</ulink>
 210         resource records. A query will be performed for each of the specified names prefixed with the port and family
 211         (<literal>_<replaceable>port</replaceable>._<replaceable>family</replaceable>.<replaceable>domain</replaceable></literal>).
 212         The port number may be specified after a colon (<literal>:</literal>), otherwise <constant>443</constant> will be used
 213         by default. The family may be specified as the first argument, otherwise <constant>tcp</constant> will be used.</para></listitem>
 214       </varlistentry>
 215
 216       <varlistentry>
 217         <term><option>status [<replaceable>LINK</replaceable>…]</option></term>
 218
 219         <listitem><para>Shows the global and per-link DNS settings in currently in effect. If no command is specified,
 220         this is the implied default.</para></listitem>
 221       </varlistentry>
 222
 223       <varlistentry>
 224         <term><option>statistics</option></term>
 225
 226         <listitem><para>Shows general resolver statistics, including information whether DNSSEC is
 227         enabled and available, as well as resolution and validation statistics.</para></listitem>
 228       </varlistentry>
 229
 230       <varlistentry>
 231         <term><option>reset-statistics</option></term>
 232
 233         <listitem><para>Resets the statistics counters shown in <option>statistics</option> to zero.
 234         This operation requires root privileges.</para></listitem>
 235       </varlistentry>
 236
 237       <varlistentry>
 238         <term><option>flush-caches</option></term>
 239
 240         <listitem><para>Flushes all DNS resource record caches the service maintains locally. This is mostly equivalent
 241         to sending the <constant>SIGUSR2</constant> to the <command>systemd-resolved</command>
 242         service.</para></listitem>
 243       </varlistentry>
 244
 245       <varlistentry>
 246         <term><option>reset-server-features</option></term>
 247
 248         <listitem><para>Flushes all feature level information the resolver learnt about specific servers, and ensures
 249         that the server feature probing logic is started from the beginning with the next look-up request. This is
 250         mostly equivalent to sending the <constant>SIGRTMIN+1</constant> to the <command>systemd-resolved</command>
 251         service.</para></listitem>
 252       </varlistentry>
 253
 254       <varlistentry>
 255         <term><option>dns [<replaceable>LINK</replaceable> [<replaceable>SERVER</replaceable>…]]</option></term>
 256         <term><option>domain [<replaceable>LINK</replaceable> [<replaceable>DOMAIN</replaceable>…]]</option></term>
 257         <term><option>llmnr [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</option></term>
 258         <term><option>mdns [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</option></term>
 259         <term><option>dnssec [<replaceable>LINK</replaceable> [<replaceable>MODE</replaceable>]]</option></term>
 260         <term><option>nta [<replaceable>LINK</replaceable> [<replaceable>DOMAIN</replaceable>…]]</option></term>
 261
 262         <listitem><para>Get/set per-interface DNS configuration. These commands may be used to configure various DNS
 263         settings for network interfaces that aren't managed by
 264         <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. (These
 265         commands will fail when used on interfaces that are managed by <command>systemd-networkd</command>, please
 266         configure their DNS settings directly inside the <filename>.network</filename> files instead.) These commands
 267         may be used to inform <command>systemd-resolved</command> about per-interface DNS configuration determined
 268         through external means. The <option>dns</option> command expects IPv4 or IPv6 address specifications of DNS
 269         servers to use. The <option>domain</option> command expects valid DNS domains, possibly prefixed with
 270         <literal>~</literal>, and configures a per-interface search or route-only domain. The <option>llmnr</option>,
 271         <option>mdns</option> and <option>dnssec</option> commands may be used to configure the per-interface LLMNR,
 272         MulticastDNS and DNSSEC settings. Finally, <option>nta</option> command may be used to configure additional
 273         per-interface DNSSEC NTA domains. For details about these settings, their possible values and their effect,
 274         see the corresponding options in
 275         <citerefentry><refentrytitle>systemd.network</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 276         </listitem>
 277       </varlistentry>
 278
 279       <varlistentry>
 280         <term><option>revert <replaceable>LINK</replaceable></option></term>
 281
 282         <listitem><para>Revert the per-interface DNS configuration. If the DNS configuration is reverted all
 283         per-interface DNS setting are reset to their defaults, undoing all effects of <option>dns</option>,
 284         <option>domain</option>, <option>llmnr</option>, <option>mdns</option>, <option>dnssec</option>,
 285         <option>nta=</option>. Note that when a network interface disappears all configuration is lost automatically,
 286         an explicit reverting is not necessary in that case.</para></listitem>
 287       </varlistentry>
 288
 289     </variablelist>
 290   </refsect1>
 291
 292   <refsect1>
 293     <title>Compatibility with <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry></title>
 294
 295     <para><command>resolvectl</command> is a multi-call binary. When invoked as <literal>resolvconf</literal>
 296     (generally achieved by means of a symbolic link of this name to the <command>resolvectl</command> binary) it
 297     is run in a limited <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 298     compatibility mode. It accepts mostly the same arguments and pushes all data into
 299     <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 300     similar to how <option>dns</option> and <option>domain</option> commands operate. Note that
 301     <command>systemd-resolved.service</command> is the only supported backend, which is different from other
 302     implementations of this command. Note that not all operations supported by other implementations are supported
 303     natively. Specifically:</para>
 304
 305     <variablelist>
 306       <varlistentry>
 307         <term><option>-a</option></term>
 308         <listitem><para>Registers per-interface DNS configuration data with
 309         <command>systemd-resolved</command>. Expects a network interface name as only command line argument. Reads
 310         <citerefentry><refentrytitle>resolv.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> compatible DNS
 311         configuration data from its standard input. Relevant fields are <literal>nameserver</literal> and
 312         <literal>domain</literal>/<literal>search</literal>. This command is mostly identical to invoking
 313         <command>resolvectl</command> with a combination of <option>dns</option> and
 314         <option>domain</option> commands.</para></listitem>
 315       </varlistentry>
 316
 317       <varlistentry>
 318         <term><option>-d</option></term>
 319         <listitem><para>Unregisters per-interface DNS configuration data with <command>systemd-resolved</command>. This
 320         command is mostly identical to invoking <command>resolvectl revert</command>.</para></listitem>
 321       </varlistentry>
 322
 323       <varlistentry>
 324         <term><option>-f</option></term>
 325
 326         <listitem><para>When specified <option>-a</option> and <option>-d</option> will not complain about missing
 327         network interfaces and will silently execute no operation in that case.</para></listitem>
 328       </varlistentry>
 329
 330       <varlistentry>
 331         <term><option>-x</option></term>
 332
 333         <listitem><para>This switch for "exclusive" operation is supported only partially. It is mapped to an
 334         additional configured search domain of <literal>~.</literal> — i.e. ensures that DNS traffic is preferably
 335         routed to the DNS servers on this interface, unless there are other, more specific domains configured on other
 336         interfaces.</para></listitem>
 337       </varlistentry>
 338
 339       <varlistentry>
 340         <term><option>-m</option></term>
 341         <term><option>-p</option></term>
 342
 343         <listitem><para>These switches are not supported and are silently ignored.</para></listitem>
 344       </varlistentry>
 345
 346       <varlistentry>
 347         <term><option>-u</option></term>
 348         <term><option>-I</option></term>
 349         <term><option>-i</option></term>
 350         <term><option>-l</option></term>
 351         <term><option>-R</option></term>
 352         <term><option>-r</option></term>
 353         <term><option>-v</option></term>
 354         <term><option>-V</option></term>
 355         <term><option>--enable-updates</option></term>
 356         <term><option>--disable-updates</option></term>
 357         <term><option>--are-updates-enabled</option></term>
 358
 359         <listitem><para>These switches are not supported and the command will fail if used.</para></listitem>
 360       </varlistentry>
 361
 362     </variablelist>
 363
 364     <para>See <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry> for details on this command line options.</para>
 365   </refsect1>
 366
 367   <refsect1>
 368     <title>Examples</title>
 369
 370     <example>
 371       <title>Retrieve the addresses of the <literal>www.0pointer.net</literal> domain</title>
 372
 373       <programlisting>$ resolvectl query www.0pointer.net
 374 www.0pointer.net: 2a01:238:43ed:c300:10c3:bcf3:3266:da74
 375                   85.214.157.71
 376
 377 -- Information acquired via protocol DNS in 611.6ms.
 378 -- Data is authenticated: no
 379 </programlisting>
 380     </example>
 381
 382     <example>
 383       <title>Retrieve the domain of the <literal>85.214.157.71</literal> IP address</title>
 384
 385       <programlisting>$ resolvectl query 85.214.157.71
 386 85.214.157.71: gardel.0pointer.net
 387
 388 -- Information acquired via protocol DNS in 1.2997s.
 389 -- Data is authenticated: no
 390 </programlisting>
 391     </example>
 392
 393     <example>
 394       <title>Retrieve the MX record of the <literal>yahoo.com</literal> domain</title>
 395
 396       <programlisting>$ resolvectl --legend=no -t MX query yahoo.com
 397 yahoo.com. IN MX    1 mta7.am0.yahoodns.net
 398 yahoo.com. IN MX    1 mta6.am0.yahoodns.net
 399 yahoo.com. IN MX    1 mta5.am0.yahoodns.net
 400 </programlisting>
 401     </example>
 402
 403     <example>
 404       <title>Resolve an SRV service</title>
 405
 406       <programlisting>$ resolvectl service _xmpp-server._tcp gmail.com
 407 _xmpp-server._tcp/gmail.com: alt1.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 408                              173.194.210.125
 409                              alt4.xmpp-server.l.google.com:5269 [priority=20, weight=0]
 410                              173.194.65.125
 411                              …
 412 </programlisting>
 413     </example>
 414
 415     <example>
 416       <title>Retrieve a PGP key</title>
 417
 418       <programlisting>$ resolvectl openpgp zbyszek@fedoraproject.org
 419 d08ee310438ca124a6149ea5cc21b6313b390dce485576eff96f8722._openpgpkey.fedoraproject.org. IN OPENPGPKEY
 420         mQINBFBHPMsBEACeInGYJCb+7TurKfb6wGyTottCDtiSJB310i37/6ZYoeIay/5soJjlMyf
 421         MFQ9T2XNT/0LM6gTa0MpC1st9LnzYTMsT6tzRly1D1UbVI6xw0g0vE5y2Cjk3xUwAynCsSs
 422         …
 423 </programlisting>
 424     </example>
 425
 426     <example>
 427       <title>Retrieve a TLS key (<literal>tcp</literal> and
 428       <literal>:443</literal> could be skipped)</title>
 429
 430       <programlisting>$ resolvectl tlsa tcp fedoraproject.org:443
 431 _443._tcp.fedoraproject.org IN TLSA 0 0 1 19400be5b7a31fb733917700789d2f0a2471c0c9d506c0e504c06c16d7cb17c0
 432         -- Cert. usage: CA constraint
 433         -- Selector: Full Certificate
 434         -- Matching type: SHA-256
 435 </programlisting>
 436     </example>
 437   </refsect1>
 438
 439   <refsect1>
 440     <title>See Also</title>
 441     <para>
 442       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 443       <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 444       <citerefentry><refentrytitle>systemd.dnssd</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 445       <citerefentry><refentrytitle>systemd-networkd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 446       <citerefentry><refentrytitle>resolvconf</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 447     </para>
 448   </refsect1>
 449 </refentry>